Poly(lactic acid) (PLA) can be derived biologically from naturally occurring sources other than petroleum and is biodegradable. However, physical limitations such as brittleness and slow crystallization may prevent easy injection molding of PLA into articles that have an acceptable degree of toughness for many applications. Extruded amorphous sheeting may also be too brittle for handling in continuous moving equipment without breakage.
It is desirable in the present invention to obtain a toughener for poly(lactic acid) that allows poly(lactic acid) compositions to be easily melt-processed into a variety of articles with an acceptable level of toughness.
Japanese patent application publication H9-316310 discloses a poly(lactic acid) resin composition comprising PLA and modified olefin compounds. Examples of those modified olefin compounds are ethylene-glycidyl methacrylate copolymers grafted with polystyrene, poly(dimethyl methacrylate), etc. and copolymers of ethylene and alpha-olefins grafted with maleic anhydride and maleimide.